Research and development of oxidation, wear and corrosion resistant materials at high temperature by surface modification using ion processing

Abstract

A multi-year project has been carried out to develop the oxidation, wear and corrosion resistant materials at high temperature for saving energy or reducing discharge of CO 2. The elementary technologies for surface modification include ion implantation and/or thin film coating. Furthermore, plasma-based ion implantation (PBII) techniques were investigated for developing ion implantation technique to the specimens with three-dimensional shapes. As a result, it was found that the ion implantation with some elements including Nb, high-temperature Nb ion implantation and Nb+C combined implantations are effective for improving the oxidation resistance of TiAl alloy. Also, fluorine PBII treatment is effective for improving the oxidation resistance of the TiAl alloy with three-dimensional shapes. Furthermore, the thin film coating of high-Al alloys such as CoNiCrAlY, TiAlN and NiCrAl provide a promising surface modification method for improving the oxidation, wear and corrosion resistance of steels and alloys at high temperature. These effects are based on formation of a protective Al 2O 3 oxide scale on material surfaces. For practical application to sliding seal materials, the TiCrN film was applied to the actual seal ring for steam turbines, and its sliding properties were successful performance. The techniques proposed in this project provide useful information for all of the material systems required to use at elevated temperature. Several results of practical applications will be presented along with laboratory test results.